OK, guys, not another bad weekend, please. I have a lot of writing to do this weekend. But the car complains.

Short story: the car hesitate during acceleration, check engine light on, yellow, steady. It never goes higher than 3000 rpm. But it can go to at least 75 mph, no problem, just slower because of the small rpm number. Haven't had the chance to get code yet.

Longer story: as you known, this is my 96 bonne with almost 138 k miles now. I just had it for about a month now but only really started to use it two weeks ago for some reasons some of you may still remember. I commute 130 miles round trip each day at 70 mph. I changed the oil and filter two weeks ago, with the famous auto-rx treatment. For those http://www.bobistheoilguy.com/ members, I am sure you are very familiar with it. It is supposed to clean up the engine and make it run even better and receives unanimous praise there. That'* why I thought it must be a good idea to use it for a high mileage car. But now I am afraid it has something to do with it. The oil and filter used were cheap walmart supertech because they should be changed out in 1500 miles, or 200 miles later. So the filter may have been clogged enough but oil pressure is fine.

The car started to hesitate a bit during acceleration sometime this week but I didn't pay too much attention. Today it declined to go higher than 3000 rpm and the check engine light came on. It still drives fine and I came back home with it, still at 70 mph. Back home earlier is more important, isn't it? I don't know how much damage has happened though. No other warning sign.

Anyway, any thoughts? Thank you very much!

I have a similar issue: http://www.bonnevilleclub.com/forum/...ic.php?t=82515

However no SES light and it will go higher than 3k RPM

It'* best to get the code rather than guess what the problem is.

What is the 'auto-rx treatment' ?

www.auto-rx.com.

The popular oil forum, http://www.bobistheoilguy.com/, has a lot of discussion about it. auto-rx is its sponsor though.

Sounds like you might be in transmission-protect "limp home" mode.

You must get the code with a scanner. Is there an Autozone near you?

IMHO, sounds like a plugged up catylitic converter.....

has there been any rattling under the car lately??? also, is there a lack of power when under load, or up around 3,000 rpm? if so, have the cat checked out ASAP... try to drive it as little as possible untill you either rule out the cat being a problem or get it replaced.

I have had the same thing happen to two vehicles I have owned and it was a plugged up cat both times

take it to a shop if you have to, but don't go out and replace it unless you know that is the problem.

OK, p0300. Random/Multiple Cylinder Misfire Detected. Man, that must be bad ones to cause the car decline to go to 3000 rpm.

I have no time to work on it this weekend. I have to start working on my writing soon. I might come back to check the forum randomly. Any thought?

I'm afraid a lot of different things can cause that code.
Do you know when the plugs & wires were changed last?
Can you check the fuel pressure?

Well, this is interesting. You guys aren't goona believe this. The light went off!

My reasoning of the situation was that this should be caused by a global problem because misfire was not limited to 1 cylinder. Then of course fuel system was a good candidate. I poured a bottle of fuel system cleaner into it and was thinking that it wouldn't cause big problems at least. And you know what, within a mile, the light went off and I was allowed to go beyong 3000 rpm again. So I decided to waste more time by taking it to the highway for ~ 35 miles. I could feel that on my way back the car responded way better and now it is just fine. Almost no acceleration hesitation.

That'* amazing. 5 bucks of prestone fuel system complete cleaner. I hope at least it will behave next week. I will have time to deal with it next weekend.

OK, last post for the day. I have already wasted a morning. Go to prepare lunch now and get back to work.

Please keep discussion though. I will check back tomorrow, if not tonight.